Sigh, having written a couple of extensions to (separately) insert HTML opening and closing tags into pages, I find that the output of those extension tags is being wrapped in <p>...</p>. This occurs even if I don't put line breaks before/after the tags (and omitting line breaks messes other things up anyway).
For example, one of my tags outputs: <span style="display:block; float:left; width:33%">
and in the HTML I get:
<p><span style="display:block; float:left; width:33%"> </p>
which is not only not what I want, but also incorrect HTML!
Thanks, Ken